Geology, Grayling River, British Columbia

Abstract

The Grayling River area (NTS 94-N/06) in the western Liard Basin is underlain by Triassic and Lower Cretaceous shale, siltstone and sandstone. A regional unconformity at the base of the Cretaceous down cuts to the north and east. Folds dominate the structural style. These probably formed in the latest Cretaceous and are well exposed along Liard River and where the resistant Liard Formation occurs. A regionally significant change in the orientation of structures from northwest in the Rocky Mountain Foothills (southern part of the area) to north or northeast in the Liard Thrust and Fold Belt (northern part of area) occurs. Cross-cutting faults and highly variable fold trends indicate local regions where both trends are developed. This map incorporates extensive observations from a major unpublished geological study of the Liard River corridor prepared for BC Hydro in 1984 as well as new data collected during field work as part of the GEM project.